Photographic pyrazolidone developers in non-aqueous organic solvents



Unite rates atent O 3,038,801 PHOTOGRAPHIC PYRAZOLIDONE DEVELOPERS IN NON-AQUEOUS ORGANIC SOLVENTS Gerald C. Alletag, Tenafly, N.J., assignor to Philip A. Hunt Company, Palisades Park, N.J., a corporation of New York No Drawing. Filed Feb. 18, 1960, Ser. No. 9,418 19 Claims. (Cl. 96-66) My invention relates to new and improved photographic developers and to a new and improved method of making the same.

The developers include a solution of a 3-pyrazolidone in a selected non-aqueous or substantially non-aqueous organic solvent. The developer may include one or more ingredients additional to the 3-pyrazolidone.

The 3-pyrazolidones are well known and are described, for example, in pages 276-277 of volume IV (published in 1957) of Chemistry of Carbon Compounds, published by Elsevier Publishing Company; and in page 484 of volume V (published in 1924) of Thorpes Dictionary of Applied Chemistry. As stated therein, the pyrazoliclones are readily oxidized to pyrazolones.

The pyrazolidone ring is as follows, viz., 1 phenyl 3 pyrazolidone:

/H (3) O=CC 4 I i\ H I f (2) HN (5) It is well known to use the class of 3-pyrazolidones as reducing agents in photographic developers and such use has been extensive for approximately a decade. Such use is disclosed in Kendall US. Patent No. 2,289,367, patented July 14, 1942, and in the corresponding British Patent No. 542,502. The member of said class which is designated as l-phenyl-3-pyrazolidone has been especially used as a reducing agent in a photographic developer, for the purpose of developing the latent image which is formed in silver halide photographic layers.

The well-known developing baths are aqueous. These aqueous developing baths, in addition to one or more reducing agents, usually contain an alkali, a preservative such as sodium sulfite, and a restrainer such as potassium bromide or benzotriazole. For commercial purposes, developers containing the 3-pyrazolidones have been sold as concentrated aqueous solutions, which have been diluted with additional water just prior to using the complete developing bath; and as well, developers incorporating 3-pyrazolidones have also been sold in powder form which, for use, have been dissolved in water.

When the aforesaid developer has been sold as an aqueous concentrate of the 3-pyrazolidones, it has often been necessary to store the same for a period as long as several years, and the storage temperature may range as high as 50 C.55C.

Experience has shown that such aqueous concentrates are not stable under commercial storage conditions. (See article by G. C. Alletag in Photographic Science and Engineering, volume 2, pages 213-218, published in 1958.) As a result of this storage instability, the finished developer bath exhibits substantial and excessive losses in speed, contrast and capacity. This has been known for at least five years.

This storage instability appears to be caused by hydrolysis and is entirely difierent from the losses of activity 3,038,801 Patented June 12, 1962 of 3-pyrazolidones which are mentioned in British Patent No. 708,479. Hitherto, storage instability has been considered to be an inevitable result of the ready oxidation of the 3-pyrazolidone and, in particular, the l-phenyl- 3-pyrazolidone.

I have discovered that B-pyrazolidones, and particularly, 1-phenyl-3-pyrazolidone, can be stored stably in dissolved form for indefinite periods and at temperatures up to C., by using selected non-aqueous or substantially non-aqueous organic solvents which fulfill the necessary requirements for compatibility with complete photographic developer compositions. I can thus commercially market a non-aqueous or substantially nonaqueous concentrate of the 3-pyrazolidone in a container, packed together with a receptacle which contains an aqueous bath of the other ingredients of the desired developer composition or contains said other ingredients in dry form. I thus prevent hydrolytic degradation of the 3-pyra'zolidone, and I mix the contents of said container and receptacle, together with any necessary dilution with water, substantially at the beginning of use. I thus provide a developer having full speed, contrast and capacity.

I can optionally dissolve in said non-aqueous or substantially non-aqueous organic solvent, one or more of the ingredients in the end mix, this in addition to the 3-pyrazolidone.

The selected organic solvent, in addition to being nonaqueous or substantially non-aqueous, must have high solubility in water at 20 C.30 C. under ordinary atmospheric pressure of 760 millimeters of mercury, or be easily and completely miscible with water under these conditions. In addition, the selected organic solvent must be compatible or non-reactive with any of the other developer ingredients, and must be non-reactive with the sensitized photographic film or layer and its paper carrier or other carrier, and it must be capable of dissolving a sufiicient ratio of the 3-pyrazolidone compound at 20 C.-30 C. under said ordinary atmospheric pressure, and it must not be unduly toxic or otherwise hazardous to use.

The selected non-aqueous or substantially non-aqueous organic solvent should dissolve at least five grams of 1-phenyl-3-pyrazolidone per one hundred milliliters of said organic solvent, at 20 C.-30 C. under said ordinary atmospheric pressure and should be capable of dissolving corresponding ratios of other 3-pyrazolidones.

Without limitation, the invention is illustrated in the following examples.

The chemicals used herein are of the commercial or technical grade.

EXAMPLE NO. 1

This consists of Part A and Part B, which are packed separately and mixed at the time of use, together with added water.

The benzotriazole is also designated as 1',2,3-benzotriazole. Its formula is C H NHN and it is well known as a photographic restrainer. It is described in page 143 of the 1956 edition of The Condensed Chemical Dictionary, published by Reinhold Publishing Corporation and Chapman & Hall Ltd.

The ethylene glycol monoethyl ether is well known as Cellosolve. Its formula is CH OHCH OC H It is described in page 240 of said The Condensed Chemical Dictionary.

The above-mentioned Part A is diluted with three parts (by volume) of water if the final mixture is to be used on a photographic emulsion with a film carrier or with 7 parts of Water if the carrier is paper. Part B is added to the diluted Par-t A, before or after Part A has been diluted.

EXAMPLE NO. 2

Part A Tetrahydrofurfuryl alcohol milliliters 10 1-phenyl-3-pyrazolidone "grams" 1.0

The formula of tetrahydrofurfuryl alcohol is C H OCH OH It is described in page 1078 of said The Condensed Chemical Dictionary.

Part A is diluted as stated in Example No. 1, and mixed with Part B.

' EXAMPLE NO. 3

Part A This is the same as in Example N0. 1.

Part B Methanol milliliters 20 l-phenyl-3-pyrazolidone grams 1.0

'Part Ais diluted as in Example No. l and mixed with Part B.

EXAMPLE NO. 4

Part A Same as in Example No. 1

Part B 1,4-dioxane milliliters l l-phenyl-B-pyrazolidone grams 1.0

The formula of 1,4-dioxane is OCH CH OCH CH It is described in page 398 of said The Condensed Chemical Dictionary.

Part A is diluted as in Example 1 and mixed with Part B.

EXAMPLE NO. 5

Part A Same as in Example No. 1.

Part B Dimethylformamide milliliters l-phenyl-3-pyrazolidone grams 1.0

The formula of dimethyl formamide is HCON(C H It is described in pages 391-392 of said The Condensed Chemical Dictionary. Part A is diluted as stated in Example No. l and is mixed with Part B.

EXAMPLE NO. 6

This discloses the preparation of a liquid developer concentrate which is suitable for use in the silver diffusion transfer process.

The formula of 2-chloro-l-ethanol, which is also designated as ethylene chlorohydrin, is CICH CH OH. It is described in page 455 of said The Condensed Chemical Dictionary.

In this example, Part A is diluted with two parts of water by volume and Part B is added to Part A before or after said dilution.

EXAMPLE NO. 7

This is for the purpose as Example No. 6.

Part A is the same as in Example No. 6.

Part B Methyl sulfoxide "milliliters" 10 1-phenyl-3-pyrazolidone grams 2.5

The formula of methyl sulfoxide is CH SOCH It is described in Handbook of Chemistry and Physics, 24th edition (1940), published by Chemical Rubber Publishing Company.

Part A is diluted as in Example No. 6; Part B is then added.

EXAMPLE NO. 8

This provides a developer for films and prints in which all the ingredients, with the exception of the developing The Condensed Chemical Dictionary. Its formula is CH OCH CH OH.

The dry powdered mixture of Part A is dissolved in one liter of water at 20 C.30 C. under normal atmospheric pressure, and the aqueous solution is mixed with Part B. No further dilution with Water is required to develop films or prints.

EXAMPLE N0. 9

Part A is the same and is used in the same manner as in Example No. 8.

Part B Diethylene gycol monomethyl ether milliliter 10 l-phenyl-S-pyr-azolidone grams 0.17 Hydroquinone do 4.0

The diethylene glycol monomethyl ether, also known as methyl Carbitol solvent, has the formula CH OHCH OCH CH OCH It is described in page 220 of said The Condensed Chemical Dictionary.

Part B is used in combination with Part A, as described in Example No. 8.

Although I have heretofore referred to different methods of mixing and dilution of the respective parts of the formulation, it is within the province of this invention to provide for variations in the order of mixing or dilution, as long as the end mix incorporates the ingreclients in the desired quantities and state of solution.

Tests have been made of the pH values of mixtures of said organic solvents with equal parts by weight of distilled water. These pH values were determined by the glass electrode at 2 0 C.30 C. These tests showed that the pH value had no effect on storage stability.

The pH value of the mixture of the respective solvent with an equal quantity of distilled water by weight is in the following table:

Solvent: pH value Methyl Cellosolve, ethylene glycol monomethyl ether 6 .25 Tetrahydrofurfuryl alcohol 4.1 Cellosolve, ethylene glycol monoethyl ether 4.1

The solution of the 3-pyrazolidone in the selected organic solvent may be packed and shipped in a completely filled and hermetically sealed glass receptacle, which is kept sealed until admixture with the aqueous component of the complete developing bath. The selected organic solvents mentioned herein are selective for the desired purpose, because they can dissolve a sufficiently large ratio by weight of the 3-pyrazolidone and they are freely miscible with water at 20 C.30 C. The hydroquinone which is mentioned in the examples represents a class of auxiliary organic developing agents, of which many are well known and can be substituted for the hydroquinone.

I have described preferred embodiments of my invention, but numerous changes, omissions, additions and substitutions can be made without departing from its scope.

I claim:

1. The method of providing an aqueous photographic developing bath including a S-pyrazolidone reducing agent, which comprises storing the 3-pyrazolidone reducing agent in a solution, said solution being substantially stable against hydrolysis, the solvent of said solution be ing organic and substantially non-aqueous, said solution being freely miscible with Water at 20 C.-30 C. the solubility of said 3-pyrazolidone in said organic solvent at 20 C.-30 C. being an amount corresponding to at least five grams of 1-phenyl-3-pyrazolidone per one hundred milliliters of said solvent, said solution being sufficiently free from water to be substantially stable against hydrolysis during a storage period of at least a year at a storage temperature of 20 C. to at least 55 C., and incorporating said solution into an aqueous medium for providing a developing bath, whereby a bath containing 3-pyrazolidone reducing agent having substantially full speed, contrast, and capacity is provided.

2. A method according to claim 1, in which the organic solvent is selected from a class which consists of ethylene glycol monoethyl ether, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, tetrahydrofurfuryl alcohol, 1,4-dioxane, Z-chloro-l-ethanol, methanol, dimethyl formamide, and methyl snlfoxide.

3. A method according to claim 1, in which the 3-pyrazolidone is 1-phenyl-3-pyrazolidone.

4. A method according to claim 2, in which the de veloping agent is l-phenyl-3-pyrazolidone.

5. A method according to claim 1 in which the organic solution includes an auxiliary organic developing agent.

6. A method according to claim 5 in which the auxiliary developing agent is hydroquinone.

7. The method of claim 1, said aqueous medium contains an alkali.

8. The method of claim 1, said solvent being ethylene glycol monoethyl ether.

9. The method of claim 1, said solvent being tetrahydrofurfuryl alcohol.

10. The method of claim 1, said solvent being methanol.

11. The method of claim 1, said solvent being 1,4-dioxane.

12. The method of claim 1, said solvent being dimethyl-formamide.

13. The method of claim 1, said solvent being 2-chloro- 1-ethanol.

14. The method of claim 1, said solvent being methyl sulfoxide.

15. The method of claim 1, said solvent being ethylene glycol monomethyl ether.

16. The method of claim 1, said solvent being diethylene glycol monomethyl ether.

17. A method of making an aqueous photographic developing bath, which consists in mixing a solution of a 3-pyrazolidone reducing agent in a substantially anhydrous organic solvent with an aqueous solution containing auxiliary developing bath agent, the solubility of said pyrazolidone in said organic solvent at 20 C.-30 C. being an amount corresponding to at least five grams of l-phenyl-3-pyrazolidone per one hundred milliliters of said organic solvent.

18. A method in accordance with claim 17 wherein the pyrazolidone is 1-pheny1-3-pyrazolidone.

19. A solution of a 3-pyrazolidone developing agent, said solution being substantially stable against hydrolysis, the solvent of said solution being organic and substantially non-aqueous, said solution being freely miscible with water at 20 C.-30 C., the solubility of said 3- pyrazolidone in said organic solvent at 20 C.30 C. being an amount corresponding to at least five grams of 1-phenyl-3-pyrazolidone per one hundred milliliters of said solvent, said solution being sufficiently free from water to be substantially stable against hydrolysis during a storage period of at least a year at a storage temperature of 20 C. to at least 55 C. said solution further having hydroquinone dissolved therein.

References Cited in the file of this patent UNITED STATES PATENTS 2,289,367 Kendall July 14, 1942 FOREIGN PATENTS 650,911 Great Britain Mar. 7, 1951 

1. THE METHOD OF PROVIDING AN AQUEOUS PHOTOGRAPHIC DEVELOPING BATH INCLUDING A 3-PYRAZOLIDONE REDUCING AGENT, WHICH COMPRISES STORING THE 3-PYRAZOLIDE REDUCING AGENT IN A SOLUTION, SAID SOLUTION BEING SUBSTANTIALLY STABLE AGAINST HYDROLYSIS, THE SOLVENT OF SAID SOLUTION BEING ORGANIC AND SUBSTANTIALLY NON-AQUEOUS, SAID SOLUTION BEING FREELY MISCIBLE WITH WATER AT 20*C.-30*C. THE SOLUBILITY OF SAID 3-PYRAZOLIDONE IN SAID ORGANIC SOLVENT AT 20*C.-30*C. BEING AN AMOUNT CORRESPONDING TO AT LEAST FIVE GRAMS OF 1-PHENYL-3-PYRAZOLIDONE PER ONE HUNDRED MILLILITERS OF SAID SOLVENT, SAID SOLUTION BEING SUFFICIENTLY FREE FROM WATER TO BE SUBSTANTIALLY STABLE AGAINST HYDROLYSIS DURING A STORAGE PERIOD OF AT LEAST 55*C., AND INSTORAGE TEMPERATURE OF 20*C. TO AT LEAST A YEAR AT A CORPORATING SAID SOLUTION INTO AN AQUEOUS MEDIUM FOR PROVIDING A DEVELOPING BATH, WHEREBY A BATH CONTAINING 3-PYRAZOLIDONE REDUCING AGENT HAVING SUBSTANTIALLY FULL SPEED, CONTRAST, AND CAPACITY IS PROVIDED.
 19. A SOLUTION OF A 3-OYRAZOLIDONE DEVELOPING AGENT, SAID SOLUTION BEING SUBSTANTIALLY STABLE AGAINST HYDROLYSIS, THE SOLVENT OF SAID SOLUTION BEING ORGANIC AND SUBSTANTIALLY NON-AQUEOUS, SAID SOLUTION BING ORGANIC AND SUBWITH WATER AT 20*C.-30*C., THE SOLUBILITY OF SAID 3PYRAZOLIDONE IN SAID ORGANIC SOLVENT AT 2/*C.-30*C. BEING AN AMOUNT CORRESPONDING TO AT LEAST FIVE GRAMS OF 1-PHENYL-3-PYRAZOLIDONE PER ONE HUNDRED MILLILITIES OF SAID SOLVENT, SAID SOLUTION BEING SUFFICIENT FREE FROM WATER TO BE SUBSTANTIALLY STABLE AGAINST HYDROLYSIS DURING A STORAGE PERIOD OF AT LEAST 55*C. SAID SOLUTION FURTHER ATURE OF 20*C. TO AT LEAST 55*C. SAID SOLUTION FURTHER HAVING HYDROQUINONE DISSOLVED THEREIN. 